An aiming telescope of the type specified above is known from U.S. Pat. No. 3,464,770.
It is well known to provide aiming telescopes with adjustment means, the so-called “turrets”, which allow to adjust the line of sight within the aiming telescope in defined steps, either along a vertical axis or along a horizontal axis. For doing so one conventionally adjusts either the aiming mark or the objective lens. When doing so, the aiming telescope that had been “shot-in”, i.e. adjusted at its manufacturing site for a certain ammunition and for a predetermined distance, may be re-adjusted such that precise shots are possible also for other distances and/or for other ammunition. Moreover, other spurious effects may be compensated for, for example a given aiming angle of the aiming telescope when the target is located at another height as the marksman, and, further, environmental influences, for example the direction or the intensity of a wind.
In some instances, aiming telescopes are additionally equipped with a range finder, in particular with a laser range finder. The laser range finder emits a very thin laser beam and computes the distance between the target and the marksman from the phase shift between the emitted beam and the beam reflected by the target. The point of impingement of the laser beam on the target may be mirrored into the aiming telescope so that the marksman has a visual control of the target point he is actually aiming at.
For that purpose, it is, of course, necessary that the laser beam and the line of sight of the aiming telescope be aligned exactly parallel (at least for large distances where the parallax has no influence) or coincide. In the last-mentioned case the range finder is integrated into the aiming telescope at least to such an extent that the laser beam is at least partially mirrored into the beam path of the aiming telescope.
Now, when the line of sight of the aiming telescope is adjusted by adjusting the aiming mark through actuation of the turrets, the parallelism or the coinciding of the line of sight and of the laser beam gets lost. The laser beam will then impinge on a point on the target that lies besides the target point that is actually aimed at.
From U.S. Pat. No. 5,771,623 there is known an aiming telescope which avoids this disadvantage by integrating the range finder into the aiming telescope, wherein the laser beam runs through the objective lens of the aiming telescope and it is the objective lens that is adjusted for adjusting the line of sight. By doing so, it is guaranteed that the laser beam and the line of sight still coincide even when the line of sight is adjusted. The emitted laser beam is mirrored into the beam path of the aiming telescope by means of a first beam splitter and the received laser beam is mirrored out of the beam path by means of a second beam splitter. Such a system, therefore, necessitates two beam splitters.
A similar solution is also known from U.S. Pat. No. 6,583,862. There, the degree of integration of the range finder is somewhat less. The range finder is configured as a unit that may be docked laterally to the aiming telescope, which,—in contrast to the solution according to U.S. Pat. No. 5,771,623 mentioned above—also opens up the possibility of an add-on solution. The range finder, when docked to the aiming telescope, is optically connected to the latter through a lateral opening. The laser beam is also mirrored into the beam path of the aiming telescope and mirrored out of the beam path by means of two beam splitters, one of which being located within the aiming telescope and the other within the docked range finder. For adjusting the line of sight a pivotably journaled inner tube is used which, inter alia, houses an inverting system and the one beam splitter.
As already mentioned above, these two prior art concepts necessitate two beam splitters each which must have a predetermined division ratio. Depending on the selection of the division ratio one either loses emitted power or received power. In any event, this results in a loss of range. Moreover, it is characteristic for this concept that the emitted laser beam as well as the received laser beam run though the objective lens together with the visual received beam. This results in reflections of the emitted laser beam at the objective lens and to errors within the received signal (so-called auto-errors).
German patent specifications DE 28 41 612 C1 and DE 36 39 326 C2 disclose devices for tanks in which a range finder is connected to the tank as a unit being entirely separate from the sighting device of the tank gun, and being adjustable in its alignment by means of a motor.
U.S. Pat. No. 3,464,770, mentioned at the outset, discloses a sighting device being coupled to a laser range finder. In this apparatus a laser emitter is arranged on top of the aiming telescope. A biconcave lens of a Galilei-system is arranged within the beam path of the laser emitter. This system apparently is used for widening the beam of the solid-state laser, as had been conventionally used at the time when this document was generated. The lens is adapted to be shifted in a vertical and in a horizontal direction transversely to the optical axis of the laser emitter. A reticle is arranged within the beam path of the aiming telescope below this lens. The reticle is likewise adapted to be shifted in a vertical and in a horizontal direction, transversely to the optical axis of the aiming telescope. This is effected under the control of control signals of a computer which computes the distance to the target from the laser emitter beams reflected from the target. The reticle and the biconcave lens are coupled mechanically, such that a shifting of the reticle in a vertical and/or in a horizontal direction effects the same shifting of the bi-concave lens in the same direction.
This prior art device has several disadvantages.
On the one hand, the direct rigid coupling between the reticle and the biconcave lens only allows a very coarse readjustment of the emitted measuring laser beam of the laser emitter relative to the line of sight.
On the other hand, the emitted measuring laser beam wanders out of the optical center of the biconcave lens when only the lens is transversely shifted whereas the laser emitter as well as the further lenses of the Galilei-system are held stationary with the housing, which results in an optical distortion of the emitted measuring beam.
Moreover, due to the shifting of the reticle the aiming mark wanders out of the center of the image field.
Further, the mechanical construction is difficult to make when the reticle is arranged in the vicinity of the eyepiece, whereas the laser emitter shall be located as close as possible to the objective lens.
Finally, the utilization of a laser emitter with a downstream optical system is disadvantageous also in view of the corresponding weight, and the optical system causes a considerable distance between the optical axes of the laser emitter and of the aiming telescope which, in turn, results in considerable parallax errors.
German patent specification DE 33 29 589 C2 discloses another aiming device with a laser emitter in which the optical axis of the laser emitter is adapted to be pivoted by laterally shifting a rotary wedge pair located within the beam path of the laser emitter. This is effected with a servomotor depending on signals of a computer which senses the rotary position of a mirror arranged within the beam path of the aiming telescope.
This device, therefore, has the same disadvantage as already discussed above, namely that the emitted measuring beam is optically distorted during pivoting.